Cubic Phase GaN on Nano-grooved Si (100) via Maskless Selective Area Epitaxy

• Published in: Advanced functional materials Vol. 24; no. 28; pp. 4492 - 4496
• Main Authors: Bayram, Can, Ott, John A., Shiu, Kuen-Ting, Cheng, Cheng-Wei, Zhu, Yu, Kim, Jeehwan, Razeghi, Manijeh, Sadana, Devendra K.
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 23-07-2014
• Subjects: cubic phase; Epitaxy; gallium nitride; Gallium nitrides; Indium gallium nitrides; maskless selective area epitaxy; Materials selection; nano-grooves; Nanostructure; Photonics; Silicon; Silicon substrates
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201304062

A method of forming cubic phase (zinc blende) GaN (referred as c‐GaN) on a CMOS‐compatible on‐axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h‐GaN) and possess very high polarization fields (∼MV/cm) along the common growth direction of . Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization‐free along the common growth direction of , however, this phase is thermodynamically unstable, requiring low‐temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano‐groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress‐free, and low‐defectivity c‐GaN on CMOS‐compatible on‐axis Si. These results suggest that epitaxial growth conditions and nano‐groove pattern parameters are critical to obtain such high quality c‐GaN. InGaN/GaN multi‐quantum‐well structures grown on c‐GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology.
Thermodynamically stable, stress‐free, and low‐defectivity GaN is integrated on CMOS Si (100) substrates. A new mask‐free local‐area epitaxy is introduced, resolving the issue of lattice and thermal mismatch between GaN and Si. A novel U‐shaped nano‐groove pattern is proposed, enabling polarization‐free cubic phase GaN. InGaN/GaN multi‐quantum‐well structures on such polarization‐free GaN/Si templates offer an ideal roadmap for (integrated) photonic devices.